This invention relates to a pin which retains a tooth tip on an adapter mounted on the lip of a dipper bucket.
A plurality of adapter-tip assemblies are mounted on the lip of a dipper bucket to scrape and dig material which goes into the bucket. Each adapter is rigidly affixed to the lip by one of several well-known means, including a C-clamp and wedge arrangement. The nose of the adapter projects beyond the lip and is received in the socket of a removable tooth tip. Aligned holes are formed in the wall defining the tooth tip socket and in the adapter. A pin is driven through one of the socket holes into the adapter hole and the opposite socket hole. The purpose of the pin is to retain the tooth tip on the adapter. When the tooth tip is to be removed from the adapter, the pin is driven out of engagement with the adapter and tip.
One type of retaining pin is a unitary assembly in which a wedge member and a lock member are joined together by a resilient member which has a rectangular cross-section and has a first pair of walls, one of which is bonded to the wedge member and the other is bonded to the lock member. The resilient member has a second pair of side walls which bulge outwardly between the lock member and the wedge member when the retainer pin is compressed. When the pin is driven through a hole in the tip socket for insertion into the adapter-tip assembly the resilient member is severly compressed. After it passes through that hole and into the hole in the adapter, which is slightly larger than and offset from the holes in the tip, the lock member snaps into place between the walls of the tip socket and the resilient member is compressed to a lesser degree. Compression of the resilient member retains the lock member in position. In order to remove the tip, the retaining pin is driven out of the adapter hole and through one of the socket holes.
It has been found that when the resilient member undergoes extreme compression, such as during insertion and removal through the holes in the tooth tip, the side walls bulge outwardly and engage or rub against the wall defining the tip hole. A problem with having the side walls bulge outwardly and engage the wall of the tooth tip hole is that it greatly increases the force required to drive the retaining pin in or out of the adapter-tip assembly. Another problem with having the side walls bulge outwardly when the pin is compressed is that, after the pin has been in position within the adapter for a period of time, very small particles of rock and ore pack securely around the retaining pin. These particles of rock and ore prevent the resilient member walls from bulging outwardly and lock the retaining pin in position.
In order to prevent the side walls from bulging outwardly in a similar pin, which is the subject of application Ser. No. 411,168 and assigned to the assignee of the instant invention, space was provided in the resilient material for the side walls to expand into when the pin was compressed during insertion or removal from the adapter-tip assembly. The space was a central cavity formed within the resilient member. However, it was found that even with a cavity in the resilient member the side walls of the member bulged outwardly away from the center of the resilient member when the member was compressed. Consequently, the pin was difficult to remove after particles of rock and ore had packed around it.
It is desirable to provide a unitary retaining pin in which a wedge member and a lock member are joined by a resilient member which is mounted between them and attached to one wall of each. Additionally, it is desirable to provide the resilient member with a means for preventing the outward bulging or expansion of its side walls when it is compressed during insertion or removal from an adapter-tip assembly.